Stiffened fabric



Oct. 6, 1942. A. F. SMITH 2,298,071

STIFFENED FABRIC Filed Oct; 18, 1940 Rid Line Q A1]: EFT Far'i 5 Emifh Patented Oct. 6, i942 UNITED S ATES PATENT,

7 STIFFENED FABRIC Albert Faris Smith, Wilmington, nel assig nor to E. I. du Pont de Nemours & Company, Wilmington Del'., a corporation of Delaware Application October is, 1940, Serial No. 361,783

moi-aims. (Cl. 139-420) This invention relates to improvements in stiffened or stifiening fabric, and more particularly to methods of imparting to fabric material predetermined stiffness in predetermined areas.

The present application is a continuation-inpart of my application Serial No. 283,082,"fi1ed July 6, 1939, which is a continuation-in-part of my abandoned application Serial No. 232,683, filed September 30, 1938. v

Heretofore horsehair has been widely used-as a stiffener element for fabrics, e. g., such as are employed for interlinings in coats, dresses, upholstery, or the like; Horsehair, however, is essentially a staple fiber and works out of the fabric so that its projecting ends cause considerable discomfort to the user. Besides causing such discomfort, the displacement or total removal of the particular strand results in weakening and loosening of the fabric structure, with consequently increasing likelihood of tearing and fraying thereof. Moreover, horsehair often is excessively bulky and does not dye satisfactorily,

even white horsehair being non-uniform in its dyeing characteristics; In addition, the-use of horsehair as a filler is attended by technical difliculties in fabrication which makeispecial procedures necessary. I Various expedients have been tried, for" the purpose of circumventing the aforesaid difficulties, or some of them. For instance, artificially.

formed threads of cellulose derivatives have been employed. But thcse'entail many of, the same disadvantages as the natural horsehair. In particular, they are very deficient in that their stifiness is greatly reduced by moisture, and ass.

rule they are excessively brittle. Furthermore, their resilience is very poor. Nor' has impregnation of threads formed from natural materials met with appreciable success, in imparting-increased rigidity to fabrics into which the samehave been incorporated.

In the case of collars, in particular, the problem of imparting adequate stiffness to the fabric and at the same time avoiding the disadvantages inherent in the userof. starch orother cementitious materials has become so acute that it has been proposed to use wires in the said fabric. Such wires, however serviceable they may be in general, necessarily are more or less deficient by reason of their metallic nature and their consequent inability to withstand repeated flexing, or corrosion.

This invention has as an object not only the minimization of the foregoing disadvantages but also the achievement of certain novel advantages hereinafter pointed out. More specifically, this invention has as a further object the construction ofa stiffened or stiffening fabric in which monofils of any desired length are employed as the stillener elements, thesaidmonofils having defined, of at least 030x10 lbs/sq. in. at 50%- a higher degree of stiffness. than polyfils of simi-- lar composition and. overall denier, but being capable ofrreadily assuming arelatively permanent set when subjected to simple and economical treatment such as specified. hereinafter. A still further object of the invention is the provision,

of a simple and economic method for varying the stiffness or-flexibility of thefabric structure in any, desired degree or gradation, as for instance-by graduallyincreasing the rigidity from areas where greater flexibility is desired toward.

areas where greater' rig idity is desired. I

The, foregoing objects, aswell as others which will appear either expressly orimpliedly hereinbelow, are accomplished by incorporating in the fabric, or employing. in reenforcing association therewith, monofils consisting of or comprising synthetic linear polyamide such as specified here-- inafter, the diameter or'denier of the saidmonofils, as wellas'their modulus of bendingelastic-f ity, being chosen or variedin accordance with therelative degrees andlocations of the rigidity or flexibility desired in' the fabric. Usuallythe said monofils, which may be employed as warp or filler, or both,.e, g.,are between 50 and 600denier.

- For many ordinary purposes, also, a range of from 20 to 150 ends per inch will be foundsatis-ffactory.

Where the completecl fabric is to. be employed as a; garment interliner, e. g.; for stiffeningcoats,

the monofils preferably should possessa degreeof intrinsic stiifness corresponding to a modulus of bending elasticity, which presently will be relative humidity and at least 0.10 l0 at 100% relative humidity, or preferably of at least 040x10 and 0.15 l0 lbs/sq. in. at'50% and 100% relative humidity, respectively. The said intrinsic stiffness of the monofils, in terms of the said modulus, is determined by placing the monofil tobe: tested across two supports, one. inch apart, applying a kriowmweight on the monofil midway'between these supports, and observing with a traveling microscope the deflection of the monofil one minute after the application of the weight. From the valuej'of this deflection, the intrinsicstifiness of'the monofi-l in terms of the i said modulus is determined by means of the/following equatiom where E=thesaid modulus of bending elasticity;

W the weight in pounds, I =the length in inches between the supports, D=the diameter of the monofil, and Ye -T1116 deflection ofithe centerin 7 inches.

Further, the degree of elastic recovery from bending should beatleast %,.in such case, and

the, monofil should beoi such a composition as" not to exhibit softening or retraction even when subjected to temperatures as high as 100 C. The said degree of elastic recovery from bending maybe measured by wrappinga 600 denier monofil ten times (angle 3600*) around a mandrel 0.111 inch in diameter, holding the monofil in this position for two minutes, releasing the monofil, and then measuring the angle retained, i. e., the angle of residual deformation (a), after the monofil has ceased to recover. The degree vof elastic recovery then may be determined by means of the following equation:

Recovery in per cent:

Although in some instances no variation of flexibility or rigidity will be desired, preferred embodiments of the invention making provision for such variation utilize the distinctive ability of the aforesaid polyamides to be extruded into relatively large monofils of whatever diameter, within wide limits,'may be desired. Thus, the polyamide stiffener monofils may be'disposed in mutually parallel relationship, each having a constant diameter throughout its length, but

with the diamtersof the different monofils becoming successively-smaller as the areas are approached where greater flexibility is desired, and successively larger as the areas are approached where greater rigidity is desired. Or, monofils fashioned with a gradual taper, in accordance with processes described in my hereinabove cited parent application, may be placed in mutually parallel juxtaposition, with their tapers all pointing in the same direction. In' such case,

the cross-sectional sizes of the monofils being the same for any given distance from the line formed by their minimum cross-sections, the rigidity of the fabric will uniformly increase as the said distance increases, and will uniformly decrease as the said distance decreases.

The polyamides which are suitable for-use in this invention are of the types described in U. S. P. 2,071,250, 2,071,253, 2,130,523, and 2,130,-

line in structure'and are oriented along their fiber axes. Orientation may also be effected by the application of compressive stress such as that which takes place in the process of cold rolling as described in Miles Ser. No. 170,470, filed October 22, 1937, and assigned to the assignee hereof,

or by a combination of tensile and compressive stresses such as takes place in the die drawing which is described in Brubaker Ser. No. 284,556,

filed July 14, 1939, also assigned to the assignee hereof.

The conditioning or setting treatment which is givento the filaments after their orientation is an important factor in determining their properties. Thus, subjection of the monofils or the fabric containing them to heat treatment in the presence of water or other mild swelling agent therefor, greatly improves their ability to recover from wrinkling or other deformation encountered in normal use. This operation may be carried out while the fabric is stretched on a tentering frame or on mandrels, or by pressing the fabric between formed surfaces in the presence of steam or hot water. At 100C. treatment for about one-half hour generally is desirable. At higher temperatures treatments for shorter periods of time may be utilized, however. For further details of this setting treatment, reference may be 'had to Miles U, S. P. 2,157,119.

, both in its broader aspects and in certain of the 948. It may be observed, in passing, with respect to the structure of the'polyamides, that they contain amide groups '5 where R is hydrogen or a monovalent hydrocarbon radical) as an integral part of the main chain of atoms in the polymer. It also may be observed that in these polyamides the average number of carbon atoms in the segments of the chain separating the amide groups is at least two. Accordingly, in this specification and the claims appended hereto, the expression, synthetic linear polyamide, is to be understood as applying to polyamides not only belonging to types described in the aforesaid patents, but also coming within the limitations pointed out in this paragraph. It will be apparent therefore that in the claims the expression synthetic linear polyamide is not intended to include non-carbonamide polymers, or polymers such as are formed I by the condensation of urea and formaldehyde.

As indicated in the above-mentioned patents,

. the high molecular weight synthetic linear polypreferred embodiments mentioned hereinabove. I Fig. 1 shows a fabric H! with which there are incorporated parallelstifiener monofils ll, each of which has a constant diameter throughout its length, but the diameters of which, as a group, are of successively smaller'sizes. At right angles to the monofils II are tapered monofils I2, these being aligned in parallel relationship with each other'and having their tapers pointing in the same direction. Both by reason of the successive decrease in the diameters of the monofils H and the parallel tapering of the monofils II, the stiffness of the fabric gradually recedes from a maximum, as depicted at the foot of the drawing, to a;minimum, as depicted attop of the drawing. Fig. 2 shows a fabric [3 in which gradual decrease of rigidity is effected merely by the parallel juxtaposition-oftapered stiffener monofils Fig. 3 shows a collar [5 having a conventional collar fabric IS with which there are associated parallel, constant diameter monofils H, the same having diameter sizes which successively decrease.

rigidity being provided in the region of the fold.

line of the collar, and the minimum flexibility and maximum rigidity being provided at the portions farthest therefrom. V

, slippage at the intersections may be prevented by subjecting the fabric to pressure in thepresence of steam orhot water to give a permanent crimp to the monofils at the points of intersection. Or, adherence between the monofils and the rest of the fabricmay be effected by the application of adhesives, or solvents for the polyamide of which the monofil is formed or for both the said polyamide and the material of the fabric.

A still further expedient for preventing slipa i 1 2,298,071 pageinvolves theincorporation of a meltin P n depressor in the surface polyamide, at the points where the monofils cross each other or cross other quently causes melting of the polyamide at the said surfaces but not at other points; which melting suffices to effect the said adherence without impairing any pre-existent orientation of the other portions of the monofils. Asa rule, substances which function as plasticizersfor the polyamide will suflice as such melting point depressors, e. g., phenols, or aryl sulfonamides boiling above 200 C. The incorporation of the melting point depressor conveniently may be effected merely by applying a solution of the same in an inert solvent, as, e. g., a saturated 50% aqueous ethyl alcohol solution of phenol, to the surface portions of the monofils corresponding to the desired points of adherence.

Although the drawing shows straight monofils only, it will be understood that the stiffener monofils of the invention, whether or not tapered, maybe disposed in any desired manner in the fabric structures. It also will be understood that for some constructions the monofils advantageously may be wrapped with polyfils of cotton nylon, or other fibers prior to the weaving or other fabric-forming operation. Usually, the monofils are most advantageously incorporated in the wrap.

The following examples are illustrative of the invention:

Example I A"-7'.5-mil (300 denier) oriented monofil is prepared from polyhexamethylene adipamide in the usual manner, care being taken that the drawn filament is not exposed to high temperature or brought in. contact with hot water or steam until the fabric is in its final form. The setting of undesirable permanent kinks or wrinkles thus is avoided. A fabric is constructed, using lengths of this monofil as the filler (65 ends per inch) with a 400 denier cotton warp (60 ends per inch) The fabric is steam pressed to set it in its final form.

' Example III A monofil is preparedwhich is in all respects similar to that of Example I, except that it tapers gradually from a maximum diameter of 0.015 inch to a minimum diameter 0.005 inch, at 4-inch intervals along its axis. The taper is imparted in accordance with the process of Example I in the is employed 'asfiller (40 ends per inch). 1 After.

yarn, of 000 denier, also-is used as warp (40 ends per inch); being disposed 'in-alternating relationship with the aforesaid monofils. and. in addition subjection to'the setting treatment described: in Example I hereinabove, thisfabric. shows marked ability to recover from deformation. On being,

out along the line connecting thethick sections of the warp,the pieces exhibit a'gradual decrease in stiffness .from the margin containing the maximum diameter ends of the 4-inch monofils tothe center and an increase toward the opposite margin. These pieces are suitable for the manufacture of collars as shown in Fig. 3.,

' In addition to filaments formed from polyhexamethylene adipamide, those prepared from poly-. hexamethylene sebacamide as well as from polydecamethylene sebacamide have been foundespecially useful in the practice of the invention, since hereinabove-cited application, Ser. No. 283,082, of v which this application is a continuation-in-part. A fabric then is constructed, using the said monofils as the warp (40 ends per inch) Cotton denier they also have a high modulus of bending elasticity, and one that decreases relatively little upon subjectionof the fabrics to conditions of, high humidity. Filaments made from other 'poly amidesof the types described in thehereinabovecited patents likewise may beused, however, e. g.,

filaments derived from G-aminocaproic acid poly mer, and from interpolyamides.

Instead of the polyamides mentioned hereinabove, which are obtainable from bifunctional polyamide-forming reactants alone, there also may be used linear polyamides which are obtained by including with the polyamide-forming reactants from which the polyamide is prepared, other bifunctional reactants, such as amino alcohols, glycols,. and hydroxy acids. N0twithstanding the fact that these products contain ester linkages, they still may be referred to as polyamides, since they contain a plurality of amide linkages in the main chain and retain many of the desirable properties of the simple polyamides. In general these polyester-amides, like :the simple synthetic linear polyamides, do not possess fiber-forming properties unless they have an intrinsic viscosity above 0.4, Where intrinsicviscosity is defined as in U. S. P. 2,130,948. Polyamides having an intrinsic viscosity between 0.6 and 2.0 are particularlysuitable for main the practice of this invention.

A further type of polyamidesuitable for use in V preparing the monofils of the invention consists of the polyurethanes which, are obtainable by reacting diisocyanates with glycols, the reaction involved being'represented as follows:

wherein n is an integer and R and R are divalent organic radicals which maybe identical or different.

It is within the scope of the invention to employ monofils which have been modified by the addition of resins, cellulose derivatives, pigments, or agents added for the purpose of increasin the stability of the polymer when exposed for long periods to sunlight or elevated temperatures. Among such stabilizing agents are phenothiazine, phenyl-a-naphthylamine, B-naphthylamine, diphenyl guanidine, and nonheat-hardening resins of the phenol-formaldehyde type such as fusible, soluble resins prepared from p-tertiary-butylphenol and formaldehyde .with the aid of an acid catalyst. Resins contribut materiallyto stiffenuuful as garment re-enforcing and stiffening fabrics. When so used, they'notonly minimize.

or avoid altogether the hereinabove-mentioned disadvantages of the prior art materials, while at the same time providing a number of new'andunique advantages, but also, asibrought out-in,

and in connection with,"Fig s-. 1 and 3 in particu lar, lend themselves to an exceedingly simple so-.

lution ofthe problem of avoiding edges between the stiffened. portions and thenon-V.

stiffened portions of garments suchas coats, collars, girdles, brassires, or the like. -Heretofore.

this-problem has elicited many efforts toward solution, but all of the prior proposals -of which the applicant'ls aware call for exp-edients and operations which are costly and cumbersome, as compared with the solution depicted in the afore I said drawing.

thefiag-pole, and gradually decreasing stiffness.

at points of increasing distances therefrom, can be put into effect very conveniently by utilizing, as the fabric, textile material such as shown in Fig.- 1' or in Fig. 2; Flags so fabricated unfurl more easily and more gracefully, other things being equal, than'conventional flags.

-As regards collars, in particular, it may b observed that, if desired, the-horizontal constant diameter-monofils -I'|,-of Fig. 3, e. g., maybe se-j lected and placed so astc have those-of greatest rather than least diameter in closest proximity to the fold line, with the respective diameters becoming successively smaller, at increasing distances therefrom. Or,-still further relationships of widely-varying scope. easily can be effected, in

respect of the arrangement of the tapering and/or the constant diameter monofils. Usually, however, a design will be chosen which, like that shown in Fig. 3, is calculated to facilitate the operation of turning a shirt collar up, before tying of a necktie in place, and turning-the shirt ployed, e. g, a e-garment inter-liners, and as or for stiflened portions in suits, e. g., coat iapels.

In short, wherever it'il desired to impart .a high degree or strengthand resiliency to the fabric structures, the stiffener monofils of the invention 'willbefound useful.

Since manyapparently widely different embodiments or thisiinvention may be made withoutdeparting from the spirit and scope thereof,

it is to be'understood that I donot limit myself to they specific embodiments thereof'except as defined in the appended claims. 7

1. A woven fabric containing; asrstiffener elements, monofils'fconsisting, principally of synthetic linearv polyamide, said monofils varying in theirrespective'. diameters .andhaving heat-set crimps therein; to prevent slippage'out of said fabricand having a count of 20 to 150 ends per inch, each'of said monofils having a substantially constant'denier in the range from to 600, a capacity for'recovering from bending of at least 85%, and a modulus of bending elasticity of at least'0.3 l0 lbs/sq. in. at 50% 'relative'humidity I 2. The woven-fabric of claim 1 in which the said synthetic linear, polyamide "is po'lyhexamethylene adipamide.

3. The woven "fabric set forth'in claim 1 in which the said monofils are present in the warp.

4. The woven' fabric set forth in claim 1 in which a resin is substantially uniformly incorporated in and through the said synthetic linear polyamide.

5. The woven fabric set forth in claim 1' in which the said synthetic linear polyamidecontains, in substantially uniform admixture therewith, a phenol-formaldehyde resin.

6. A woven fabric ?containing, as stiffener, ele-- ments, monofils consisting principally of-synthetic linear polyamide, each ofsaid monofils taperinggradually from a maximum diameter to a ,minimum "diameter and: being disposed collar down, after such tying; i. e., so as to minii mizethe wrinkling usually involved or threatened in such operations. It is'to be noted, in this connection, that where the necessary stiffness in collars is secured by means of thisinvention, rather than by means of starch, e. g., the collars are substantially ncn-wiltable in use, even in the hottest weather.

Over and above their special usefulnes in the elimination of the edges" in question, according to the methods set forth hereinabove. the stiffener monofils of the invention exhibit out-' standing stiffeners, generally, and consequently are appropriate for .use in a wide variety ofmaterials in addition to those already mentioned, e. g., in neckbands, shirt fronts, hats, necktie interlinings, and upholstery fabrics, as wellas in me.- chanical fabrics such as belting and press cloths. Thus, for instance. the said fabrics generally will be found particularly well adapted for application where hair cloth heretofore has been emthroughout one direction of said fabric with their taperspointing in .the same directionand having the small sections of said monofils in lateral alignment.

7.. A woven fabric containing, as stiffener elements, monofils consisting principally of synthetic linear polyamide, each of said-monofils tapering gradually from a maximum diameter to a minimum diameter and again to a maxi-' mum diameter, said tapered monofils being disposed throughout one direction. of saidfabric with their tapers pointing inthe same direc superiority over prior art fabric tionand having the small sections of said monofils in lateral alignment. 7

8. A woven fabric containing, as stiffener elements, monofils consisting principally of synthetic linear polyamide, each ,of said monofils having-a plurality of recurrent portionsgradually tapering from a maximum diameter to a minimum diameter and again to a maximum diameter, said tapered monofils being disposed throughout one direction of said fabric with their tapered portions pointing in the some direction and having the smallv sections of said monofils in lateralalignment.

9. A woven fabric containing, as stiffener elements monofils consisting principally of synthetic linear polyamide, certain of said monofils tapering gradually from a maximum diameter to a minimum diameter and being disposed throughout one: direction of said fabric with their tapers pointing in the same direction and having the small sections of said monofils in lateral alignment, certain other of said monofils having a substantially uniform diameter along their length and being disposed throughout the other direction of said fabric in substantially mutual parallel relationship. V

10. A woven fabric containing, as ments, monofils consisting principally of synthetic linear polyamide, each of said monofils having a substantially uniform diameter along its length, said monofils varying in their respective diameters and being disposed throughout one direction of said fabric substantially in the order in which their diameters successively decrease.

11. In a stand-up container, a woven wall fabric containing, as stiffener elements, monoflls' consisting principally of synthetic linear polyamide, each of said monofils tapering gradually from a maximum diameter at the bottom of said wall fabric to a minimum diameter at the top thereof, said tapered monfils being vertically disposed in said wall fabric with their small sections in lateral alignment whereby greater stiffness is obtained at the bottom of said wall fabric than at the top thereof.

12. In a collar, a woven fabric containing as stiffener elements, monofils consisting principally of synthetic linear polyamide, each of said monofils having a substantially uniform diameter along its length, and being disposed in substantially parallel relationship with the fold line of said collar, said monofils having diameter sizes which successively decrease with proximity tosaid fold line whereby maximum flexibility is obtained at said fold line.

stiffener ele- 13. A woven fabric containing, as stiffener elements, monofils consisting principally of syntheticlinear polyamide, said monofils having heat-set crimps there in to prevent slippage out of said fabric, certain of said monofils tapering gradually from a maximum diameter to a minimum diameter and being disposed throughout one direction of said fabric with their tapers pointing in the same direction and having the small sections of the monofils in lateral alignment, certain other of said monofils varying in their respective diameters but each monofil having a substantially uniform diameter along its length, said last mentioned monofils being disposed throughout the other direction of said fabric with their diameters decreasing toward the small sections of the tapered monofils.

14. A woven fabric containing, as stiffener elements, monofils consisting principally of synthetic linear polyamide, said monofils having heat-set crimps therein to prevent slippage out of said fabric, certain of said monofils tapering gradually from a maximum diameter to a minimum diameter and being disposed throughout one direction of said fabric with their tapers pointing in the same direction and having the small sections of the monofils in lateral alignment, certain other of 'said monofils being disposed throughout the other direction of said fabric and having a count of 20 to 150 ends per inch, each of said other monofils having a substantially constant denier in the range from to 600, a capacity for recovering from bending of at least and a modulus of bending elasticity of at least 0.3)(10 lbs/sq. in. at 50% relative humidity.

ALBERT FARIS SMITH. 

